YCCD 1-17-17

Major and Minor NPDES Permit Modifications and Required Items for Submittal

What is considered a major modification to the NPDES permit?

  • the revision or future phase is located outside the original approved NPDES permit boundary
  • the NPDES permit is being reduced in area to remove permit coverage from a previously covered area
  • the revision or future phase proposes a new point source discharge to a receiving surface water
  • the revision or future phase will result in a discharge to a new receiving surface water not named in the original permit
  • the revision or future phase is located outside the limit of disturbance shown on the overall conceptual E&S plans (i.e. outside the “total disturbed area” listed on the NOI) and the existing approved E&S BMPs are not adequate to minimize accelerated erosion and sedimentation. The “total disturbed area” is defined as, “that portion of the total project area where earth disturbance activities are planned to occur over the life of the project. For phased projects, this refers to the disturbed area of the initial project phase plus the planned disturbed areas of subsequent project phases.”
  • therevision or future phase proposes an increased PCSM discharge (ex. net runoff volume increase for the 2 year/24 hour storm event and/or peak runoff rate increase for the 2 year/24 hour through 100 year/24 hour storm events with the PCSM BMPs in place) to any existing approved Point of Discharge.
  • the revision or future phase does not satisfy the pollutant reduction requirements of PCSM Worksheets 11, 12, and 13 (where a net runoff volume increase is proposed for the 2 year/24 hour storm event with the PCSM BMPs in place)

What is considered a minor modification to the NPDES permit?

  • the revision or future phase is located outside the original approved limit of disturbance but within the original approved NPDES permit boundaryprovided on the original permitted phase or overall conceptual E&S plan and the existing approved E&S BMPs are adequate to minimize accelerated erosion and sedimentation.
  • Minor field adjustments or modifications to the approved E&S and/or PCSM plans that do not affect the adequacy of the original approved E&S and/or PCSM BMPs located within the original approved limits of disturbance

What items are required for a major modification?

  • A new NOI checked as a “major modification.” All items required for a new NPDES NOI (see NOI Completeness Checklist).
  • Only the additional disturbed area outside the original approved limit of disturbance should be listed in NOI Section B.3. The $100 disturbed acre fee is based only on the additional disturbed acreage.
  • Application & Fee for District Services. Fee is based only on the additional disturbed acreage.

What items are required for a minor modification?

  • Revised E&S and/or PCSM plan drawings and narrative. PCSM narrative should include infiltration testing/geotechnical report and all supporting calculations. E&S and PCSM plans are required to be consistent and to be the final plans for construction.
  • Application and Fee for District Services is required only when major changes (ex. street and lot layout) are proposed to the approved E&S plans significantly changing the E&S BMP design requiring a technical E&S plan review. Application and Fee for District Services are not required for minor modifications related only to the PCSM plan and not requiring a technical review of the E&S plans.
  • Completed Section D of the current NOI application demonstrating no increased discharge (ex. no net runoff volume increase for the 2 year/24 hour storm event and/or no peak runoff rate increase for the 2 year/24 hour through 100 year/24 hour storm events with the PCSM BMPs in place).
  • PCSM Worksheets 1-5 & 10.
  • PCSM Worksheets 11, 12, & 13 (where a net runoff volume increase for the 2 year/24 hour storm event is proposed with the PCSM BMPs in place).